The major areas of research include development of new methods for long range cloning gene enrichment, isolation of DNA protein complexes and rapid detection and isolation of cis and trans elements involved in the regulation of the cell type and host range specificity of viral DNA replication and transcription. These and related approaches will be applied to analysis of gene regulation in the SV40 system and in the expression of proteins of immunologic importance as well as in an analysis of the control of development of various T cell subsets.